Abundance ratios of selected ice molecules to water ice as a function of the radius in simulations M_TD, M_10, and M_0, plotted on a common y-axis scale to ease the comparison. Profiles are shown for two different values of the central H₂ density: 10⁵ (red) and 10⁷ cm⁻³ (blue). Solid, dashed, and dotted lines correspond to simulation M_TD, M_10, and M_0, respectively. The light green bands show the ratios derived from observations toward low-mass young stellar objects (Boogert et al. 2015).